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Chapter 12 - BC Scie
Terms and questions
Term | Definition |
---|---|
Continental Drift Theory | A theory that the continents have not always been in there present locations but have moved there over millions of years. |
Names of fossils found: | Mesosaurus, cynogathus, lystrosourus, glossopteris |
Pangaea | The "super continent," when the continents were one. |
Wagner proposed his theory based on(3): | Fossils Region Climate including paleoglaction |
Tectonic Plates | The large slabs of rocks that form Earth's surface, moving over a layer of partly molten rock |
Volcanoes | An opening in Earth's surface that when actives spews out gases, chucks of rocks and melted rock. |
Earthquakes | A ground shaking release of built up energy at or under Earth's surface. |
Mid-Atlantic Ridge | The longest mountain range on Earth, running from North to South down the middle of Atlantic Ocean. |
Oceanographer | A person who studies the ocean floor |
Magnetic Reversal | The process in which Earth magnetic field, over thousands of years, completely reverses its direction |
Palemagnetism | The study of magnetic properties in ancient glaciers |
Magnetic Striping | A pattern of alternating stripes of different directions of magnetic polarity in rock on the sea floor. |
Magma | Molten rock beneath Earth's surface |
Spreading Ridge | The region where magma breaks through the Earth's surface, continually forcing apart old rocks and forming a new sea floor |
Floor Spreading | a process in which new ocean floor is created as molten material from the earth's mantle rises in margins between plates or ridges and spreads out. |
Hot Spot | An area where molten rocks rises to Earth's surface |
Plate Tectonic Theory | The theory that the lithosphere is broken up into large plates that move and then rejoin. |
Lithosphere | The layer of Earth made up of the crust and mantle, and ranging thickness of 65km to 100km |
Earth's crust | Earth's outermost layer formed by lighter materials, such as silicon and oxygen, floating on the top during Earths cooling period. |
Crust's thickness and composition | Continental Crust- Made of granite, 70km thick Oceanic Crust- made from a dense and dark rock called basalt, 10km thick |
Mantle | Earth's thickest layer, lying just below the crust, and making up 70% of the Earth's volume |
Mantle's thickness and composition | Thickest layer (2900km thick), solid, divided into 2 parts (upper and lower mantle) |
Outer Core | The layer below Earth's mantle |
Outer Core's thickness and composition | Outer core is liquid(2300km thick)composed mainly of a mix of turc or iron and nickel |
Inner Core | Earth's solid center |
Inner Cores's thickness and composition | Radius (1200km), composed of iron and some nickel. Temp -5000*c to 6000*c |
Asthenosphere | A partly molten layer in Earth upper mantle, just below the lithosphere |
Mantle Convection | A reoccurring current in the mantle that occurs when hotter, less dense materials rises, cools, and then sinks again.This current is believed to be one of the driving forces behind the tectonic plate movement |
Rift Valley | A steep sided valley formed on land when magma rises to Earth's surface at a spreading center. |
Ridge push | The process in which new material at a ridge or rift pushes the old material aside. |
Subduction | When one plate goes under another |
Subduction zones | An area of subduction, typically where earthquakes and volcanoes occur |
Slab Pull | The pulling of a tectonic plate as its edge subducts deep into the mantle |
Plate boundry | The region where two tectonic plates are in contact |
Divergent plate boundaries | A region where tectonic plates are spreading aprart |
Divergent plates | Tectonic plates that are spreading apart |
Convergent plate boundary | A region where tectonic plates are colliding |
Converging plates | tectonic plates that are colliding |
Oceanic- continental plate convergence | When an oceanic plate and continental plate collide and the oceanic plate is forced beneath the continental plate, this creates a deep underwater valley called Trench. |
Trench | A deep underwater valley |
Volcanic belt | A chain of volcanoes |
Oceanic-Oceanic plate convergence | When two oceanic plates collide and subdiction occurs. cooling will causes one plate to be denser than the other and the denser plate will slide another |
volcanic Island Arc | A chain of volcanic islands |
Continental- continental plate convergence | When continental plates collide subduction does not occur since the plates are similar densities. |
Faults | Large breaks in rock layers |
Transform Fault | a fault that occurs at a transform plate boundary. |
Focus(foci) | the location in earth at where the earthquake starts |
Epicentre | the point on earths surface directly above the focus where an earthquake starts |
Seismic waves | vibrations caused by the energy released by an earthquake |
seismology | the study of earthquakes and seismic waves |
Surface Waves (L - Waves) | Waves that ripple along Earth's surface |
Surface waves | travels along earths surface and is last to arrive (slowest) |
Primary Waves (P - waves) | a type of seismic body (underground) wave that travels at about 6km/s through earths crust |
Primary waves | travels through solid, liquid and gas and is first to arrive (fastest) |
Secondary waves( S - waves) | a type of seismic body (underground) wave that travels at about 3.5km/s causing the ground to move in perpendicular to the direction of the waves motion |
Secondary waves | travels through solids but not liquids and is second to arrive (slower) |
Seisometers | devices that measure the amount of ground motion caused by an earthquake and recorded on a seismo grah |
seismogram | a record of ground motion |
Earthquakes magnitude | Magnitude is a measure of the amount of energy released during an earthquake |
Composite Volcanoes | cone shaped volcanoes: the cone shapes is the result or repeated eruptions |
shield volcanoes | volcanoes that form over hot spots: the largest volcanoes on earth |
Rift Eruptions | volcanoes that occur where magma erupts through long cracks in the lithosphere where tectonic plates are spreading apart |